Method and machine for producing details from a sheet of metal

ABSTRACT

A method and a machine for producing plate components (1) from a sheet of metal (2) which is moved through a press (13) for at least a first cutting operation to be performed to separate the plate components from the sheet of metal and a second cutting operation to separate scrap (27), said press being open with a space (32) allowing free insertion of the metal sheet. According to the invention the metal sheet is displaced by means of a feeding device (11) between the metal working operations, following a predetermined coordinate pattern and being machined in consecutive y-sections (24, 26) each y-section (24) being fully machined in x-direction before the immediately following y-section (26) is brought into position for machining, the metal sheet being machined within surface areas (33), each of which has a length in x-direction of at most 30 cm, and is larger than the plate component so that a peripheral, unbroken scrap portion (27) remains after the first cutting operation. The second cutting operation is performed to sever a scrap portion (27) by cutting at an angle so that a trimmed side edge (28) is formed and at the same time a trimmed edge (35) across the y-section (24). Furthermore, displacement of the metal sheet is controlled by a programmable control unit which also controls the movements of the metal working tools as desired.

This application is a 371 of PCT/SE93/00820, filed Oct. 11, 1993.

This application is a 371 of PCT/SE93/00820, filed Oct. 11, 1993.

The present invention relates to a method of producing plate componentsof varying size and shape from a flat sheet of metal having a thicknessof from 0.1 to 20 mm which is displaced stepwise in its plane through atleast one press for at least two metal working operations to beperformed comprising a first cutting operation to separate the platecomponents from the sheet of metal, and a second cutting operation,separate from the first cutting operation, to remove scrap formed at thefirst cutting operation, said press being of the type having an uppertool stand for first parts of at least two metal working tools for saidtwo metal working operations, and a lower tool stand for othercomplementary parts of each metal working tool so that the upper andlower tool stands define a space between them for free insertion of themetal sheet in its direction of feed, said space having a depth inhorizontal direction that is Greater than the dimension of one platecomponent measured perpendicular to said direction of feed, the metalsheet having an original dimension perpendicular to said direction offeed that is several times greater than the plate component measured inthe same direction. The invention also relates to a sheet metal workingmachine for producing plate components of varying size and shape from aflat sheet of metal having a thickness of from 0.1 to 20 mm, comprisingat least one press having an upper tool stand for first parts of atleast two metal working tools and a lower tool stand for othercomplementary parts of each metal working tool, these tool standsdefining a space between them for free insertion of the metal sheet inits direction of feed, said space having a depth in horizontal directionthat is greater than the dimension of one plate component measuredperpendicular to said direction of feed, the metal sheet having anoriginal dimension perpendicular to said direction of feed that isseveral times greater than the plate component measured in the samedirection, which metal working tools are arranged to perform first andsecond cutting operations to separate the plate components from themetal sheet or to separate scrap, the machine also comprising a feedingdevice with gripping means to firmly retain the metal sheet and to moveit stepwise in relation to the press, and a horizontal table located ina plane with the upper surface of the lower tool stand containing saidother complementary tool parts.

Plate components are usually produced from a continuous metal stripwhich is supplied from a coil to a punching machine by means of a rollerfeeder located immediately before the punching machine. The width of themetal strip is selected depending on the size of the plate components tobe produced, in order to reduce waste in the sheet metal remaining afterthe components have been punched out. This method is used primarily whenlarge series of components of the same type are to be cut. However, itis unsuitable for smaller series of identical plate components since forreasons of cost and space a large assortment of coils of metal strip ofdifferent widths cannot be maintained and a coil of metal strip of thedesired width for a particular plate component may not be available atthe time the client places his order. The described method using metalstrip on coils thus means that the price per unit becomes too high forsmall series and sometimes even for medium-sized series of identicalplate components, or different plate components with similar dimensionexcept for the wall thickness in the initial work operation. Twodifferent techniques are used in order to reduce the unit price forsmall and medium-sized series of plate components, both of which startwith plate in the form of a rectangular sheet of standard format, knownas "cut-to-size sheet metal". According to one of these techniques thecut-to-size sheet is cut into a plurality of identical rectangularstrips, the width of which adapted to the relevant plate component.After this extra work phase, which requires separate equipment, themetal strips are usually transferred to the conventional punchingmachine used for machining said continuous metal strip. The metal stripsare fed into the punching machine by said roller feeder. The othertechnique is based on nibbling. The cut-to-size sheet metal is movedgradually through a nibbling machine with a nibbling tool that cutsthrough the cut-to-size plate with small cutting movements in rapidsuccession along a predetermined curve in order to form blanks of platecomponents. Two or more small bridging sections remain uncut so that theplate component blank remains attached to the nibbled plate. This isthen transferred to a device for removing the plate component blanksfrom the coherent scrap portion of the cut-to-size plate remaining, thebridging sections being destroyed by being cut away, for instance. It isdifficult at this stage to align and stack the plate component blanksfor further machining. Furthermore, in order to achieve the finishedplate component in a machine with single-tool, the tool must be changedafter each metal working operation a number of times, depending on theshape of the plate component.

The two techniques described, starting from cut-to-size sheet metal, arenot rational since they are complicated to perform and require extraequipment. These deficiencies and drawbacks result in the price per unitbeing unacceptably high.

The object of the present invention is to achieve an improved method andmetal working machine that essentially reduce the above-mentionedproblems and enable the production of plate components or blankstherefor in a simple way and at an acceptable unit price.

The method according to the invention is characterized in that the metalsheet is displaced stepwise between the metal working operationsfollowing a predetermined coordinate pattern the x-axis of whichcoincides with the direction of feed of the metal sheet through thepress; that the metal sheet is machined in consecutive y-sectionsextending in x-direction between the front and rear ends of the metalsheet and defined by a free side edge of the metal sheet and animaginary line parallel to the side edge and said x-axis; that oney-section is fully machined by stepwise displacement of the metal sheetin x-direction before the next y-section is brought into position formachining, the metal sheet being machined within identical consecutiveparallelogram-shaped surface areas, each of which has a length inx-direction of at most 30 cm, and is larger than the plate component sothat a peripheral, unbroken scrap portion remains after the firstcutting operation; that the second cutting operation is performed tosever one such unbroken scrap portion, or at most three unbroken scrapportions of a surface area or of at most three consecutive surfaceareas, respectively, provided the two or three surface areas togetherhave a length of at most 30 cm; that said scrap severance is performedby cutting at an angle by said second cutting operation so that atrimmed side edge is gradually formed along said imaginary line and atthe same time a trimmed edge fitting the first edge is formed across they-section; that, after one y-section has been completely removed, themetal sheet is stepwise displaced in y-direction a distancecorresponding to the width of a y-section so that an immediatelyfollowing y-section is aligned with the press, and at a chosen timebetween the moment when the metal sheet leaves the press and the momentwhen it is returned in the opposite direction to its direction of feed,to its initial position upstream of the press; and that the displacementof the metal sheet is controlled by a freely progammable control unitwhich also controls the movements of the metal working tools eithersynchronously or asynchronously with each other, as desired.

The metal working machine according to the invention is characterized inthat the feeding device is provided with an actuator for stepwisedisplacement of the metal sheet in relation to and through the pressfollowing a predetermined coordinate pattern, the x-axis of whichcoincides with the direction of feed of the metal sheet through thepress; that said metal working tool for the second cutting operation forscrap severance is designed and arranged to cut at an angle so that atrimmed side edge is formed along an imaginary line located parallel tothe direction of feed of the metal sheet and at the same time a trimmededge fitting the first side edge is formed across the y-section withinwhich metal components are produced; and that the metal working machineincludes a freely progammable control unit arranged to controldisplacement of the metal sheet in accordance with said coordinatepattern and to control the movements of the metal working tools eithersynchronously or asynchronously with each other, as desired.

The invention will be described in more detail in the following, withreference to the accompanying drawings.

FIG. 1 is a perspective view of a metal working machine according to afirst embodiment of the invention.

FIG. 2 is a view in a different perspective of the metal working machineaccording to FIG. 1.

FIG. 3 is a view of a part of a metal sheet which has been partiallymachined in order to produce bowl-shaped washers.

FIG. 4 illustrates how the metal sheet decreases as it passes throughthe machine shown in FIG. 1.

FIG. 5 shows in perspective a metal working machine according to asecond embodiment of the invention.

FIGS. 1 and 2 show schematically a metal working machine for producingplate components 1 from a flat, rectangular metal sheet 2 which, seen inits direction of feed F, is defined by a transverse front end edge 3, atransverse rear end edge 4, a longitudinally running first side edge 5and a longitudinally running second side edge 6 (see FIG. 2). The metalworking machine comprises a stand 7 supporting an oblong table 8 with ahorizontal surface on which the metal sheet 2 rests and is displacedstepwise in its plane parallel with the longitudinal direction of thetable, first forwards for machining, and then returning along the table8 without leaving it, to be set in a new position for machining. Themetal working machine comprises lifting and travelling equipment 9 fortransferring the metal sheets 2 from a stack 10 to the table 8. It isalso provided with a feeding device 11 with an actuator 36 for forceddisplacement of the metal sheet 2 in its plane on the table. The feedingdevice 11 has a plurality of gripping devices 12 to firmly retain themetal sheet 2. The metal working machine shown in FIG. 1 is providedwith a press 13 located close to and inside one long side of the table,the press having four metal working tools 14, 15, 16, 17, whereas themetal working machine according to FIG. 5 is provided with a first press18 with three metal working tools 19, 20, 21, and a second press 22 witha special metal working tool 23 consisting of a tool cutting at an anglefor trimming the metal sheet after the plate components have beenremoved. The press is of the open type, generally having an upper toolstand 30 for first parts of at least two metal working tools and a lowertool stand 31 for other, complementary parts of the metal working toolsso that the upper and lower tool stands 30, 31 define a space 32 betweenthem (see FIG. 2) for free insertion of the metal sheet 2 in itsdirection of feed F. Such a press is sometimes called a C-press. Thedepth of the space 32 in horizontal direction is greater than thedimension of a plate component 1 measured perpendicularly to saiddirection of feed F, the metal sheet 2 having an original dimensionperpendicular to said direction of feed, that is several times greaterthan the plate component 1 measured in the same dimension.

The feeding device 11 for displacement of the metal sheet 2 is arrangedto move the sheet 2 in accordance with a predetermined coordinatepattern, the x-axis of which coincides with the direction of feed F ofthe metal sheet 2 through the press, the feeding device 11 beingcontrolled by signals from a control unit (not shown). The latter alsocontrols connection and disconnection of said metal working tools eithersynchronously or asynchronously. The control unit is pre-programmed bythe operator, depending on the shape of the plate components 1 to beproduced. The metal sheet 2 is aligned by the feeding device 11 so thata first outer y-section 24 thereof is situated in front of the firstmetal working tool 14. This outer y-section is defined by the front andrear end edges 3, 4, one or first side edge 5 and the imaginary borderline 25 parallel to this side edge, from the following inner, secondy-section 26. The metal sheet 2 is fed forward stepwise in x-directionand stops in the press/presses (FIG. 1/FIG. 5) in which the metalworking operations are to be performed as predetermined by choice ofmetal working tools. The entire outer first y-section 24 is machined inthis manner, as illustrated in FIG. 4. To enable machining of the next,i.e. the second y-section 26, the metal sheet 2 is displaced acorresponding distance in y-direction so that it is again aligned withthe metal working tools. This displacement in y-direction may take placebefore or after the metal sheet 2 has been returned in a directionopposite to the direction of feed F to a starting position before thepress, or during this return movement. The displacement one step iny-direction to align each following y-section 26 preferably occurs afterthe metal sheet 2 has been returned to a starting position before thepress. One y-section 24 is thus fully machined by stepwise displacementof the metal sheet 2 in x-direction, before the next y-section 26 isbrought into position for machining, the metal sheet 2 thus beingmachined within identical, consecutive parallelogram-shaped surfaceareas 33, each having a maximum length of 30 cm in x-direction and beinglarger than the plate component 1, so that a circumferentially unbrokenscrap portion 27 (see FIG. 3) is left when the plate component 1 hasbeen removed. A subsequent cutting operation is then performed afterfull step feeding, in order to remove an unbroken scrap portion 27 or atmost three coherent unbroken scrap portions 27 of one surface area 33 orat most three consecutive surface areas 33 provided the length of thetwo or three surface areas 33 is maximally 30 cm. In the embodimentshown the surface areas 33 are quadratic. This trimming of the metalsheet 2 is preferably performed continuously as each plate component 1is removed from the metal sheet 2. Finally a completely new, straight(linear), outer, trimmed side edge 28 is obtained in the metal sheet 2which has decreased in size by one y-section 24. The cutting tool 17; 23for trimming the metal sheet is provided with an angular cutter toenable simultaneous cutting in two directions. Scrap severance is thusperformed by means of angular cutting so that a straight, trimmed sideedge 28 is gradually formed along said imaginary border line 25, and atthe same time a straight (linear) trimmed edge 35 across the y-section24. In the case shown the edge 35 is perpendicular to the side edge 28.The angular cutting may alternatively be performed so that the edge 35is inclined forwards or backwards depending on the shape (contour) ofthe plate component.

The press according to FIG. 1 has a combined sequence tool ormulti-station tool, in which three different part-operations areperformed individually one after the other in order to produce a platecomponent 1, the metal sheet 2 thus being fed one step forward for eachpart-operation. The first tool 14 makes a hole in the metal sheet, whilethe second tool 15 in the sequence performs cutting and pressing of asurface area 33, in which a hole was made in the preceding step, inorder to produce a finished plate component 1 in the form of a washer.The third tool 16 removes a previously completed washer 1 which is thenstacked in a box or the like below. The combined sequence tool is alsoprovided with a fourth tool 17 for trimming the metal sheet 2 at anangle as described previously, so that the scrap portion 27 of eachsurface area 33 is cut away in the form of a complete, flat piece asillustrated in FIG. 3.

In the metal working machine shown in FIG. 5 the first press 18 isprovided with a combined sequence tool in which three differentpart-operations are performed in the manner described above, and thecutting tool 23 for trimming the metal sheet 2 is arranged in theseparate, second press 22. This press is suitably synchronized with thefirst press 18.

The metal working machine is universal in that, with the aid of varioustool appliances, it is able to perform a plurality of metal workingoperations depending on which plate component is to be produced. Besidescutting (punching), these operations may include one or more of thefollowing: drawing, embossing, bending, pressing, drilling and screwthreading. The metal working machine may also be provided with extraequipment such as welding equipment, riveting unit, nibbling unit, etc.

The presses may be operated pneumatically, hydraulically or mechanically(eccentrically).

Complete tools, single-station tools or combined tools may be used aswell as sequence tools.

The metal working machine according to the invention can advantageouslyuse the same tools as are used in conventional punching machines forcoiled metal strip. It is then a simple matter to move the tool from onemachine to the other for larger or smaller series. The new metal workingmachine can also be used with advantage for pre-treated metal sheets,such as painted sheets, sheet coated with plastic or having text orinstructions printed on them, etc.

The metal sheets shown and described above are rectangular in shape,which is normal. However, the invention may of course be used for metalsheets of any other shape. Essential is that the metal sheet is retainedby a feeding device that displaces the metal sheet in a coordinatepattern of the type specified, where the abscissa corresponds to thedirection of feed F of the metal sheet through the press.

As mentioned, the metal sheet has an original width several timesgreater than the width of the plate component measured perpendicular tothe direction of feed F. The original width of the metal sheet issuitably at least 3 times, perferably 4 times greater than the width ofthe plate component to be produced.

The invention enables the production of plate components of arbitrary,i.e. varying size and shape, in a simple manner and at an acceptableprice per unit. The size of the plate component is limited only by thedepth of the press selected, measured in the plane of the metal sheet.All metal working operations and displacements of the metal sheet areprogrammed as desired with regard to various periods of time, startingfrom a reference position for the metal sheet resting on the table nearthe press and in position for a first feed step. The scrap pieces formedare easier to handle since they are flat and peripherally unbroken andtherefore take up less volume.

I claim:
 1. A method of producing plate components from a flat sheet of metal having a thickness of from 0.1 to 20 mm using a press with at least first and second working tools, the plate being larger than at least three plate components; each plate component having a length along an x-axis of the press and a width along a y-axis of the press, and the plate having first and second longitudinal edges, substantially parallel to the x-axis and each other, and first and second transverse edges substantially parallel to the y-axis and each other; said method comprising the steps of automatically and substantially sequentially:(a) feeding the plate into operative association with the press so that a first corner of the plate at the intersection of the first longitudinal and transverse edges is aligned with the first metal working tool; (b) acting on the plate at the first corner with the first cutting tool to at least partially form or separate a metal component from the plate at the first corner and so that a continuous piece of scrap metal is formed; then (c) incrementally moving the plate in the x-direction so that the first corner is advanced into operative association with the second metal working tool; then (d) with the second cutting tool removing the scrap, with a maximum dimension along the x-axis of 30 mm, from the plate while forming a third longitudinal edge substantially parallel to the x-axis and a third transverse edge substantially parallel to the y-axis, forming a new first corner at the intersection of the first longitudinal edge and third transverse edge; (e) repeating steps (a)-(d) to elongate the third longitudinal edge until all the metal components between the first and third longitudinal edges have been removed; then (f) moving the metal plate in the y-direction the width of the next metal component to be formed and moving the metal plate in the x-direction approximately the length of the metal plate so that a new corner thereof is positioned approximately at the position of the first corner in step (a); and (g) repeating steps (a)-(e), and step (f) if necessary, until all desired components have been formed from the metal plate.
 2. A method as recited in claim 1 wherein steps (a)-(c) are repeated once or twice before step (d) is practiced.
 3. A method as recited in claim 2 wherein steps (a)-(c) are repeated twice before step (d) is practiced.
 4. A method as recited in claim 1 wherein the press has a third metal working tool between the first and second tools along the x-axis; and comprising the further steps between steps (b) and (c), of: (h) incrementally moving the plate so that the first corner is aligned with the third metal working tool, and then (i) acting on the plate with the third metal working tool to at least partially form or separate a metal component in the plate; and wherein steps (h) and (i) are repeated when steps (b) and (c) are repeated.
 5. A method as recited in claim 4 wherein steps (b) and (i) are practiced to completely form and separate each metal component from the metal plate.
 6. A method as recited in claim 4 wherein steps (b) and (i) are practiced to form substantially circular metal components, and step (d) is practiced to substantially simultaneously cut the third longitudinal and transverse edges.
 7. A method as recited in claim 1 wherein steps (a)-(g) are practiced under the control of a programmable controller.
 8. A method as recited in claim 4 wherein the press has a fourth metal working tool between the third and second tools; and comprising the further steps, between steps (i) and (c), of: (j) incrementally moving the plate so that the first corner is aligned with the fourth metal working tool, and then (k) acting on the plate with the fourth metal working tool to at least partially form or separate a metal component; and wherein steps (j) and (k) are repeated when steps (h) and (i) are repeated.
 9. A method as recited in claim 8 wherein steps (b), (i) and (k) are practiced to completely form and separate each metal component from the plate.
 10. A method as recited in claim 9 wherein steps (b), (i), and (k) are each practiced to effect at least one of cutting, bending, pressing, drawing, embossing, drilling, or screw-threading.
 11. A method as recited in claim 1 wherein the press has a third metal working tool between the first and second tools along the x-axis; and comprising the further steps between steps (b) and (c), of: (h) incrementally moving the plate so that the first corner is aligned with the third metal working tool, and then (i) acting on the plate with the third metal working tool to at least partially form or separate a metal component in the plate; and wherein steps (h) and (i) are repeated when steps (b) and (c) are repeated.
 12. A method as recited in claim 11 wherein the press has a fourth metal working tool between the third and second tools; and comprising the further steps, between steps (i) and (c), of: (j) incrementally moving the plate so that the first corner is aligned with the fourth metal working tool, and then (k) acting on the plate with the fourth metal working tool to at least partially form or separate a metal component; and wherein steps (j) and (k) are repeated when steps (h) and (i) are repeated.
 13. A method as recited in claim 1 wherein steps (a)-(g) are practiced to produce all the metal components of the same size and configuration.
 14. A method as recited in claim 1 wherein steps (b) and (d) are practiced to work on the metal plate synchronously.
 15. A method as recited in claim 1 wherein steps (b) and (d) are practiced to work on the metal plate asynchronously.
 16. A sheet metal working machine comprising:an upper tool stand having at least first and second different metal working tool components; a lower tool stand having at least first and second metal working tool components complementary to said upper tool stand tool components, to form first and second metal working tools; said tool components of said upper and lower tool stands spaced from each other a first distance, which is greater than the thickness of sheet metal to be acted upon thereby; feeding means for feeding sheet metal between and into alignment with, and way from, said upper and lower tool stands in an incremental manner along both x and y axes; said first tool components spaced from said second tool components along said x-axis; said second tool components defining a cutting tool having first and second substantially right angled portions parallel to said x and y axes, respectively, said first portion having a maximum working length along the x-axis of 30 cm; and a programmable controller for automatically controlling operation of said feeding means and first and second tools to form at least four metal components from a piece of sheet metal, said programmable controller comprising means for controlling said feeding means to move a piece of sheet metal in increments equal to the length of each metal component formed in said x-axis, in operative association with said tools, and after an x-axis elongated strip has been separated from the piece of sheet metal incrementally moving the piece of sheet metal the appropriate width of one metal component in the y-axis, and the approximate length of the piece of sheet metal in the x-axis.
 17. A machine as recited in claim 16 wherein said first tool is in a first press, and said second tool in a second press spaced from said first press along said x-axis.
 18. A machine as recited in claim 16 further comprising third and fourth tools between said first and second tools along said x-axis.
 19. A machine as recited in claim 18 wherein said first, third, and fourth tools each comprise bending, pressing, drawing, embossing, cutting, or screw threading tools.
 20. A machine as recited in claim 17 further comprising third and fourth tools between said first and second tools along said x-axis, said first, third, and fourth tools each comprising bending, pressing, drawing, embossing, cutting, or screw threading tools. 